spacetoday.net: Dark energy unlikely to cause violent end to universe

Posted: Sat, Feb 21, 2004, 9:28 AM ET (1428 GMT)
Astronomers announced Friday that dark energy, a mysterious force that appears to cause the expansion of the universe to accelerate, will not change enough to cause a violent end to the universe for at least the next 30 billion years. Astronomers used the Hubble Space Telescope to look for distant supernovae in an effort to determine how the rate at which the universe is expanding is changing. They concluded that the expansion is accelerating at a rate consistent with the cosmological constant, a factor introduced last century by Albert Einstein to balance the attractive forces of gravity; Einstein had later dismissed the factor as a "blunder". If the repulsive force of dark energy changed over time, it could have violent consequences: an increase could cause a "big rip" if the force became strong enough to rip apart matter, while a decrease could allow gravity to take over and collapse the universe into a "big crunch". The Hubble findings show that dark energy's force appears constant enough to prevent either scenario from happening for at least 30 billion years, more than twice the current age of the universe. Instead, the universe will continue to expand, causing stars and galaxies to recede from one another.